Projectile



Oct. 10, 1967 J. w. SARVIS 3,345,948

PROJECTILE Filed Aug. 5, 1965 l 2 Sheets-Sheet 1 INVENTOR. JOHN W SARVIS TT RNEYS Oct. 10, 1967 J. w. SARVIS 3,345,948

PROJECTILE Filed Aug. 5, 1965 2 Sheets-Sheet 2 INVENTOR. JOHN W. SAR VIS wwmw ATTORNEYS 3,345,948 PROJECTILE John W. Sarvis, R0. Box 1325, Springfield, Mass. 01101 Filed Aug. 3, 1965, Ser. No. 477,045 3 Claims. (Cl. 10287) The invention described herein may be manufactured and used by or for the government for governmental purposes without the payment to me of any royalty thereon.

The invention relates to a projectile used in ammunition, and particularly to a projectile provided with means for reducing the aerodynamic drag during flight of the projectile.

An object of this invention is to provide a projectile which, during flight, uses hot gases flowing over its surface to thus reduce the drag.

Another object of this invention is to provide a projectile of the above type wherein cooperating elements act to generate the hot gases at a prescribed distance from a launcher.

A further object of this invention is to provide a projectile of the aforesaid type wherein a gas generating charge is disposed in an internal cavity of a projectile and is arranged to be initiated by means of an inertia force caused by the acceleration of a propelled projectile.

A still further object of'this invention is to provide a projectile of the character described wherein the hot gases generated flow to the outer surface of the projectile through a passageway formed by an arrangement of the projectile body and a separable nose section therefor.

Further objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the structure possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is a view in elevation, and partly in cross-section of a projectile embodying the invention;

FIG. 2 is a view taken along the line 2-2 of FIG. 1;

FIG. 3 is a view taken along the line 33 of FIG. 1;

FIG. 4 is a view similar to FIG. 1 showing diagrammatically the flow of hot gases when a projectile embodying the invention is in flight;

FIG. 5 is a front view of an element of the embodiment of FIG. 1 showing further details of construction.

As is well known in the aerodynamic art when a body is moved through the air, a friction force tangential to the surface of the body opposes the motion. This opposing friction force is commonly termed drag.

This drag is due to the viscosity of the fluid through which the body is passing, in this case air. More specifically, the drag is produced by the viscous shear in the layers of the air immediately adjacent to the body. Furthermore, when air flows past a surface, the layer immediately adjacent to the surface adheres to it. This layer is called the boundary layer. An increasing thickness of boundary layer increases the drag force on the body. The thickness of the boundary layer may be reduced by increasing the velocity of the fluid passing over the surface and/ or reducing the kinematic viscosity thereof. Viscosity of fluids generally decrease with an increased temperature. Thus, suffice it to say without entering into cumbersome technical proofs that a desirable condition for decreasing drag would be to pass a high temperature gas at a high velocity over the surface of the body in flight.

nited States Patent The present invention applies this condition to a projectile used in ammunition to reduce drag thereon thus improving the range of the projectile and the accuracy at which it can be directed.

Referring to the drawings, in which like reference characters refer to like parts throughout the various figures, and referring particularly to FIG. 1, 10 is generally a projectile used in conventional gun launched ammunition. The launching means and other elements of a round of ammunition are not disclosed herein because they form no part of this invention.

The projectile 10 comprises a body 12 having a chamber or cavity 14 therein, closed at the rear and open at the front. A gas generating charge 16 is disposed in the rear end portion of the cavity 14. The charge 16 may be of any type Well known to one skilled in the munitions art which will produce hot combustion gases while doing substantially little or no damage to the body 12. The amount of charge 12 will be determined in regard to the type projectile used. A conventional primer 18 is in operative communication with the charge 16, in this embodiment abutting therewith. A holder 20 fixed in the cavity 14 and coaxial therewith retains the primer in its relationship with the charge 16. As is shown in FIG. 3 the holder 20 is comprised of four forwardly extending legs 22 radially spaced about the circumference of an imaginary cylinder.

A firing mechanism 24 is disposed in the cavity 14 forwardly of the primer 18. The firing mechanism 24 comprises a body 26 having firing pin 28 on its rearward end facing the primer 18, and a flange 36 on its forward end. The body 26 is coaxial with the cavity 14 and is in slidable relationship with the legs 22 of the holder 20 which act as a guide between the firing mechanism 24 and the primer 18. The flange 3t abuts the wall of the cavity 14 in an enlarged portion 32 thereof and is in slidable relationship therewith. The enlarged portion 32 of the cavity 14 defines an annular shoulder 34. Helical coil springs 36 in compression abut the shoulder 34 and portions of the rearward face of the flange 30. Two springs 36 are illustrated here and may vary in number and type in accordance with particular applications. The springs 36 act to urge a force against the firing mechanism 24 to retain it in a fixed space relationship with respect to the other elements within the cavity 14. The force on the firing mechanism 24 exerted by the springs 36 is such that it will be overcome by a rearwardly directed inertia force resulting from the acceleration of the projectile 10 upon launching. 'Ihe specific applications will determine these data. As is shown by FIG. 5 the flange 3t) has four angularly spaced openings 38 extending therethrough. This function of these openings 38 will become apparent further on in this disclosure.

A nose section 4% completes the forward end of the porjectile 10. A cylindrically shaped elongated rearward portion 42 of the nose section 40 extends into the cavity 14 and terminates at the forward face of the flange 30. The cavity 14 forwardly of the enlarged portion 32 (and the flange 30) is a tapered section 43 having a shape somewhat similar in configuration to a segment of a para-boloid of revolution. The significance of the shape of this tapered section will become apparent further on in this description. A plurality of tapered retainers 44, in this case four, are force wedged in between the elongate portion 42 and the wall of the tapered section 43 of the cavity 14 and integrally fixed thereto to retain the nose section 40 Within the body 12.

The nose section 4% is in fixed space relationship with the forward end portion of the body 12, as is clearly shown in FIGS. 1 and 4.

The substantially straight surface of the elongated portion 42 and the curvilinear surface of the tapered section 43 of the cavity 14 cooperate to form a forwardly converging nozzle section 45 which will act to accelerate the hot combustion gases from the charge 16 passing therethrough. The forward end 46 of the body 12 has a curvilinear configuration convex in longitudinal cross section. The nose section 40 defines a concave portion 48 at the forward end of the elongated portion 42 which concave portion 48 complements the convex forward end 46 of the body 12 to form an annular passageway 50 from the surface of the body 12. The passageway 50 in essence is a continuation of the nozzle section 45 forming the exciting portion thereof. Thus, the passageway 50 communicates with the cavity 14 via the nozzle section 45 and has its exit directed towards the rear of the projectile body 12. As can be readily seen from the figures an unimpeded flow path exists between the gas generating charge 16 and the outer surface of the body 12.

FIG. 4 illustrates a projectile 10 in flight after being launched. When the projectile body 12 reaches a prescribed acceleration the inertia force acting thereon causes the firing mechanism 24 to overcome the force of the springs 36. The firing pin 28 impinges on the primer 18 which detonates and in turn ignites the charge 16. Hot combustion gases are thus formed and flow to the outer surface of the body 12 via the flow path formed between the cavity 14 wall and the elements therein and the passageway 50. The hot gases will continue to fiow along the outer surface of the body 12 towards the rear thereof. The nozzle section 45 of the flow path will cause the gases to accelerate to impart an increased velocity thereto. The hot gases will therefore move along the outer surface of the body 12 at a relatively high velocity thereby diminishing the thickness of the boundary layer on the surface with a resulting decrease in drag forces.

Since certain changes may be made in the above structure without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. i

I claim:

l. A projectile comprising a body having an outer surface of revolution with a tapered forward end and a nose portion secured to said projectile forward end,

cavity means within said projectile aligned with a longitudinal axis thereof,

a gas producing charge within said cavity,

passage means for directing gases emitted from said charge rearwardly from said tapered forward end and radially outwardly from said longitudinal axis, said means including a circumferential surface on a rearward end of said nose portion and a second circumferential surface on said tapered body forward end, said circumferential surfaces structurally correlated to define a nozzle at said outer surface of revolution, and

ignition means responsive to a prescribed inertial force resulting from an initial acceleration of said projectile, said ignition means being located in said cavity forwardly of said charge.

2. The projectile as defined in claim 1 wherein said initiating means includes a primer in operative contact with said charge, and

a forwardly biased rearwardly directed firing pin located within said cavity forward of said charge, said firing pin operatively contacting said primer in response to a predetermined forward acceleration of said projectile.

3. The projectile as defined in claim 1 wherein said nose portion has an ogival shaped forward outer peripheral surface and a rearwardly elongated stem positioned partially within said cavity coaxially with said longitudinal axis, said nose portion further having a rearwardly concave surface of revolution extending intermediate said stem and said outer peripheral surface.

References Cited UNITED STATES PATENTS 1,450,579 4/1923 Chilowsky 1026Q BENJAMIN A. BORCHELT, Primary Examiner,

ROBERT F STAHL, Examiner. 

1. A PROJECTILE COMPRISING A BODY HAVING AN OUTER SURFACE OF REVOLUTION WITH A TAPERED FORWARD END AND A NOSE PORTION SECURED TO SAID PROJECTILE FORWARD END, CAVITY MEANS WITHIN SAID PROJECTILE ALINGED WITH A LONGITUDINAL AXIS THEREOF, A GAS PRODUCING CHARGE WITHIN SAID CAVITY, PASSAGE MEANS FOR DIRECTING GASES EMITTED FROM SAID CHARGE REARWARDLY FROM SAID TAPERED FORWARD END AND RADIALLY OUTWARDLY FROM SAID LONGITUDINAL AXIS, SAID MEANS INCLUDING A CIRCUMFERENTIAL SURFACE ON A REARWARD END OF SAID NOSE PORTION AND A SECOND CIRCUMFERENTIAL SURFACE ON SAID TAPERED BODY FORWARD END, SAID CIRCUMERENTIAL SURFACES STRUCTURALLY CORRELATED TO DEFINE A NOZZLE AT SAID OUTER SURFACE OF REVOLUTION, AND IGNITION MEANS RESPONSIVE TO A PRESCRIBED INERTIAL FORCE RESULTING FROM AN INITIAL ACCELERATION OF SAID PROJECTILE, SAID IGNITION MEANS BEING LOCATED IN SAID CAVITY FORWARDLY OF SAID CHARGE. 